The use of dental prostheses with dental implants secured in the upper or lower jawbone is well known in the art. Accurate placement of the implants within the jawbone is a difficult task. The dental surgeon typically has difficulty deciding on a drilling axis for the implants since the ideal position for the implants should be decided with knowledge of the jawbone structure into which the implant is to be inserted, and with knowledge of the position within the jawbone structure of the nerve tissue, the gum surface and the required position and dimensions of the false teeth or dentures to be supported by the dental implant.
The conventional surgical procedure for installing one, implant-supported, prosthetic tooth includes drilling a properly positioned hole in the jawbone of the patient, inserting the implant in the hole, and attaching the prosthetic tooth to the implant. Proper implant positioning is also extremely important to ensure that the implant is anchored within sufficient bone structure in the patient's jawbone.
The most common method for locating a dental implant hole is to visually survey the area and drill the hole in a freehand manner. However, this method can readily result in imperfect bores due to space limitations associated with working inside a patient's mouth. If the drilling axis is not properly chosen, the installed implants might cause damage to the tissues and muscle surrounding the area of implantation and subsequently cause temporary or permanent paresthesia. Furthermore, other problems can result from flawed or imperfect implant holes, such as uneven force distribution, insufficient bone growth around the implant, secondary infections, and ultimately, implant failure.
During a one-stage surgical procedure, a healing abutment assists in the healing, formation, and maintenance of the soft tissue over the implant while bone integration occurs. The healing abutment is immediately placed into the implant well to ensure that the gum line will heal properly and look natural once the final abutment is tapped into the implant.
During a two-stage surgical procedure, a cover screw is initially screwed into the implant well. The tissue surrounding the cover screw is then sutured to protect the implant site while bone integration occurs. Once the bone has integrated, an incision is made in the tissue above the site, at which time integration is checked. Once the bone has healed properly, the cover screw is then removed, and a healing abutment is screwed into the implant well. With the healing abutment securely in place the tissue surrounding the area is sutured. Approximately 4-6 weeks later, the healing abutment can be removed and a final abutment is then placed into the implant. In some surgical cases, a final abutment is immediately placed into the implant well rather than the healing abutment and sutures are not required. In both the one-stage and two-stage surgical procedure, the final abutment supports the final crown or denture.
Many types of surgical guides are on the market today. They can be tooth supported, gum supported, or bone supported. The simplest guides are done in the laboratory. They consist of acrylic templates (or stents), or teeth, both filled with radiopaque markers that provide the position of the teeth in relation to the bone on 2D radiographs. Holes are drilled through these surgical guides at the selected implant sites and the surgeon uses them to make bone perforations. Afterwards, the surgeon needs to raise a flap in order to make the osteotomies. More sophisticated guides use Ct-scan data and special software in order to place the implants according to three-dimensional (3D) data. The guide is then fabricated using stereolithographic machines or milling machines.
Each surgical stent commonly used is custom-built and these devices are only useful for a single patient, are costly to fabricate, and they require a number of intermediary office and laboratory steps to take an impression of the patient's arch and create a cast model from which the surgical stent is formed.
Superstructures are used as load-bearing elements that interface prosthesis to implants. In the conventional method for the construction of superstructures, a physical model of the patient's gums and dental implant heads is prepared on which the superstructure is built manually using molding and other techniques known in the art. The craftsman or technician skilled at manufacturing such dental superstructures takes into consideration the size and shape of the desired dentures to be placed over the superstructure when crafting the same. The procedure for manufacturing dental implant superstructures as is conventionally known in the art is time-consuming and sometimes results in imperfect structures or defects in the visual appearance of the dentures to be placed over the superstructure.
Therefore, in an effort to reduce costs and the number of steps associated with fabricating a traditional surgical stent, various forms of prefabricated surgical stents and positioning guide systems have been developed to aid the dental surgeon. In International patent application publication no. WO 94/26200, there is described an adjustable guiding device for positioning dental implants in which it is possible for the dental surgeon to adjust a drilling axis for each implant before proceeding to use the guiding device or drill template to guide the surgeon's drill for the purposes of preparing the drill hole for the implant.
In U.S. Pat. No. 5,401,170, there is disclosed a method and apparatus for measuring by camera image the implant heads of the implants in the patient's mouth for the purposes of cutting a frame on which the prosthetic teeth will be arranged and baked. In the method disclosed, the construction of the frame or superstructure is carried out in the absence of a reference to the shape and position of the patient's ideal tooth position.
Thus, as the dentures or artificial teeth are crafted on the frame or superstructure, care would be required during the manual process to ensure that the position of the teeth on the frame will match the opposed set of teeth in the patient's mouth.
It would thus be desirable to provide a drill guide system comprising components fabricated prior to the actual surgery that may be used more than once for the same patient, for any restoration configuration, and that enables precise implant spacing, and also ensures that the implant holes are drilled at the proper angle and orientation.